Latch mechanism for retractable ball pens adaptable for automatic assembly



1952 F. VAN HALTERN. JR., ETAL LATCH MECHANISM FOR RETRACTABLE BALL PENS ADAPTABLE FOR AUTOMATIC ASSEMBLY Filed Aug. 7, 1959 J a 4 a o z MN 4 a w M 9... w w w w H1 1 w z 1 WWW .6 \kfi u a a? W n Muir?? ATTQRNEYJ ite States This invention relates generally to writing instruments such as retractable ball pens, and more particularly to an improved latch mechanism for writing instruments of this sort that is uniquely adapted not only for simple and efiective operation, but also for automatic, as distinguished from manual, assembly to provide for exceptionally efficient and economical manufacture.

The latch mechanism of the present invention is of the type disclosed in copending application Serial No. 631,771, filed December 31, 1956, now Patent No. 2,930,354, issued March 29', 1960, in which a latch member is arranged to float freely in a barrel for actuation by a related plunger member so as to rock oppositely in sidewise fulcrumed relation against the inner wall of the barrel for alternate latching engagement with the barrel to hold a writing unit selectively at a projected or retracted position with respect to the barrel.

According to the improved arrangement of the present invention, the latch member and plunger member are both formed symmetrically about their longitudinal axes so that they find a proper operating relation with respect to each other simply by insertion in the barrel, and consequently can be mechanically fed for such insertion to constitute a latch mechanism without requirin the slightest aligning manipulation beyond directionally orienting their respective rearward and forward ends with respect to the barrel, which is easily done mechanically.

The improved latch mechanism of the present invention further incorporates a related arrangement of latch and plunger members by which no fixed or keyed longitudinal sliding alignment of these members with the barrel is required, while still providing for opposite rocking of the latch member by the plunger member in substantially a single transverse plane passing through the longitudinal axis of the barrel as the latch member is operated for the above noted selective latchin engagement.

These and other features of the present invention are described in further detail below in connection with the accompanying drawings, in which:

FIG. 1 is a side elevation, partly in section, of a writing instrument incorporating the improved latch mechanism of the present invention;

FIG. 2 is an enlarged transverse cross section taken substantially at the line 22 in FIG. 1;

FIG. 3 is an enlarged fragmentary longitudinal section taken substantially at the line 33 in FIG. 2, and illustrating the latch mechanism of the present invention with the latch member thereof shifted longitudinally to projected position in preparation for latching engagement thereat; and

FIG. 4 is an enlarged fragmentary longitudinal section corresponding generally to FIG. 3, without showing the pocket clip, and illustrating further the disposition of the latch member when engaged at its forward or projected position and the related disposition of the plunger member for subsequently disengaging the latch member to permit its return to retracted position.

Referring now in detail to the drawings, and more particularly at first to FIG. 1, the illustrated writing instrument, as indicated generally by the reference numeral 10, comprises a composite barrel formed by forward and rear barrel portions 12 and 14 that are arranged for securing Patented Nov. 6, 1962 assembly at their respective rear and forward ends; the rear end of the forward barrel portion 12 being necked and exteriorly threaded at 16, and the forward end of the rear barrel portion 14 being interiorly threaded at 18, for such securing assembly if desired, with an interposed finishing ring 20.

The forward barrel portion 12 is further formed at its forward end with a terminal bore 22 for slidably fitting the ball point portion 24 of a Writing unit 26 arranged therein for shifting longitudinally between retracted and projected positions with respect to the forward terminal bore 22, as indicated respectively in full and dotted lines in FIG. 1. Additionally, the forward barrel portion 12 is shouldered interiorly at 28 to form a rearwardly facing seat for a biasing spring 30 applying therefrom a rearward bias on the writing unit 26 at a shoulder clip 32 or the like thereon.

The rear barrel portion 14 is in turn formed with a rear end terminal bore 34 of reduced diameter and is interiorly shaped forwardly of this terminal bore 34 with opposite longitudinal ribs 36 and 38 (compare FIGS. 1 and 2) extending respectively to terminate forwardly at longitudinally spaced latching shoulders 40 and 42; the longitudinal spacing of these latching shoulders 40 and 42 corresponding to the desired extent of longitudinal shifting of the writing unit 26 between retracted and projected positions. In addition, the rear barrel portion 14 has opposed longitudinal guiding ribs 44 and 46 formed interiorly thereof, in transverse or right angular relation and of equal width and depth with respect to the longitudinal ribs 36 and 38, and extending forwardly of the terminal bore 34 in an extent reaching just short of the retracted position latching shoulder 41 the respective longitudinal ribs 36, 38, 44, and 46 accordingly being regularly spaced at intervals interiorly about the rear barrel portion 14 and thereby allowing a pocket clip 14' to be staked in place, as seen in FIGS. 1, 2 and 3, in straddling relation with respect to any one of these longitudinal ribs so that the attachment of the pocket clip 14' does not require alignment at any particular side of the rear barrel portion 14.

The improved latch mechanism of the present invention is arranged for operation within the above described rear barrel portion 14, and is constituted by a latch member and related plunger member that are indicated generally by the respective reference numerals 48 and 50. As previously noted, the latch and plunger members 48 and 50 are characterized by an entirely symmetrical form about the longitudinal axes thereof; the latch member 48 being specifically shaped in the illustrated embodiment with a rearwardly extending cylindrical shank portion 52 that is rounded rearwardly to provide a rear end pointed configuration, as indicated at 54, and that is shouldered annularly adjacent its forward end to provide an annular latching shoulder or flange at 56. In this form, the latch member shank portion 52 is adapted, at the rounded portion thereof forwardly of the rear end pointed configuration '54, to bear against the inner wall of the rear barrel portion 14 for rocking thereat in a sidewise fulcrumed relation such as is described in the previously noted Patent No. 2,930,354. Forwardly of the annular latching shoulder 56, the latch member 48 is further shaped to present a forwardly directed rocking portion 58 rockably engaging or bearing at the rear end of the writing unit 26.

The related plunger member 50 is specifically shaped symmetrically about its longitudinal axis with a rearwardly extending cylindrical shank portion 60 proportioned for slidably fitting the rear end terminal bore 34 of the rear barrel portion 14, and with a forward portion 62 of enlarged diameter slidably fitting within the rear barrel portion 14 forwardly of the terminal bore 34. As thus arranged, the plunger member 50 is entirely free to rotate with respect to the rear barrel portion 14 about its longitudinal axis, and the forward enlarged portion 62 thereof is additionally shaped to present a forwardly facing contact surface, for actuation of the latch member 48, which may have a simple conical configuration, if desired, but in the illustrated embodiment is specially arranged with four regularly spaced radial grooves 64 contiguouslyv formed on axes inclined rearwardly from the longitudinal axis of the plunger member 50 and defined by the intersection of planes that in turn define the grooves 64 with intersecting slanted sides.

In operation, the latch member 48 is disposed to float freely within the rear barrel portion 14 and follows a particular operating motion therein by reason of the interaction of actuating forces imposed thereon by depression of the related plunger member 50 in opposition to the rearward biasing force applied through the writing unit 26 from the bias spring 30, and in relation to the rocking and latching arrangement of the latch member 48 with respect to the rear barrel portion 14 as is described in detail below.

Assuming that operation starts with the latch member 48 in retracted position as indicated in full lines in FIG. 1, the annular latching shoulder 56 will be engaged with the barrel latching shoulder 40, and the rearward biasing force applied through the writing unit 26 will have caused the rearwardly extending latch member shank portion 52 to bear sidewise against the inner wall of the rear barrel portion 14, at the rounded shape of the latch member shank portion 52 just forwardly of its pointed rear end configuration 54.

Upon subsequent depression of the plunger member 50 for shifting the writing unit 36 to the projected position indicated by broken lines in FIG. 1, the operating contact of the plunger member 50 with the latch member 48 is such as to cause one of the radial grooves 64, at the forwardly facing plunger contact surface, to find the pointed rear end configuration 54 of the latch member 48 and apply thereat an actuating force effecting the previously mentioned sidewise fulcrumed rocking of the latch member 48 against the inner wall of the rear barrel portion 14, so as to rock the forwardly arranged annular latching shoulder 56 transversely in the direction of the opposite projected position latching shoulder 42, while the latch member 48 is concurrently caused to shift 1ongitudinally forward as depression of the plunger member 50 is continued to project the writing unit 26.

The rocking of the latch member 48 in the above indicated manner, which is described as taking place against the inner wall of the rear barrel portion 14, takes place actually against the inwardly facing surface of the longitudinal rib 36 that has the retracted position latching shoulder 40 formed at the forward end thereof. Also, opposite rocking of the latch member 48 takes place against the corresponding opposed face of the opposite longitudinal rib 38, while the sliding depression of plunger member 50 is guided between these opposed faces of the longitudinal ribs 36 and 38 and between the correspondingly opposed faces of the longitudinal guiding ribs 44 and 46.

In this connection, it should also be noted that as the plunger member 50 is free to rotate about its longitudinal axis in this guided relation, and as the radial grooves 64 are formed on rearwardly inclined axes and have intersecting slanted sides, the initial contact of the plunger member 50 with the latch member 48 will result first in causing one of these radial grooves 64 to find the rear end pointed configuration 54 of the latch member 48, and to seat thereat squarely with any necessary rotation of the plunger member 50 that is required to effect such square seating. The result of this initial square seating of the radial groove 64 at the rear end pointed configuration 54 is in turn to cause the slanted sides thereof to effect a subsequent guided rocking of the latch member 48 in substantially a single transverse plane within the rear barrel portion 14.

Upon shifting of the writing unit 26 to projected position, the latch member 48 will likewise be shifted forwardly to a longitudinal extent allowing the annular latching shoulder 56 thereof to rock beneath the projected position latching shoulder 42, formed at the forward end of the longitudinal rib 38, for latching engagement therewith as illustrated at 48' in FIG. 3. When the downward actuating pressure is subsequently released from the depressed plunger member 56, the rearward bias imposed through the writing unit 26 from the bias spring 30 will thereupon apply a moment of force causing the latch member 48 to pivot about the portion of the annular latching shoulder 56 engaged at the projected position latching shoulder 42 until the rearwardly extending latch member shank portion 52 is brought to bear against the inwardly directed face of the longitudinal barrel rib 38, as illustrated in broken lines at 48" in FIG. 3.

As this pivoting of the latch member 48 takes place, the plunger member 50 having had the downward actuating pressure released therefrom, and being freely slidable in the rear barrel portion 14, will be displaced rearwardly in the necessary extent to allow the latch member pivoting, and the ultimate result is a disposition of the latch member 48 at a reset relation with respect to the plunger member 50 as illustrated in FIG. 4; this reset relation being such as to dispose the latch member 48 so that upon a succeeding depression of the plunger member 59 the plunger actuating force will cause rocking of the latch member 48 in a direction opposite to its previous rocking and thereby disengage the annular latching shoulder 56 from the projected position latching shoulder 42, to permit return of the writing unit 26 to its retracted position determined by engagement of the annular latching shoulder 56 again with the retracted position latching shoulder 40 and opposite resetting of the latch member 48 thereabout to assume its original position and relation to the plunger member 50 for subsequent projected position latching of the writing unit 26 upon the next actuating depression of the plunger member 50.

Beyond the advantageous arrangement of the latch mechanism of the present invention for consistent and effective operation in the above described manner, the essentially simple structural interrelation of the latch member 48 and plunger member 50, together with the fact that both of these members have an entirely symmetrical shape about the longitudinal axes thereof, provides the further substantial advantage of rendering automatic or mechanized assembly of the latch mechanism readily possible as has been previously noted.

For such assembly, it is only necessary to provide for successively introducing first the plunger member 50 and then the latch member 48 at the forward end of the rear barrel portion 14, with the respective rearward shank portions 52 and 60 of these members oriented rearwardly with respect to the barrel portion 14, and utilize the influence of gravity to cause the successively introduced plunger member 50 and latch member 48 to seat rearwardly in the barrel portion 14, whereupon they will necessarily assume a proper operating alignment. Such successive introduction of the plunger member 50 and latch member 48 in oriented relation can obviously be accomplished easily with any conventional hopper feeding means arranged for oriented feeding of such articles, and the latch mechanism of the present invention can thereby be completely constituted within the rear barrel portion 14 without any manual attention whatever beyond what may be involved in maintaining a feeding supply of the structural parts involved.

Having the latch mechanism thus automatically constituted in the rear barrel portion 14, it only remains to assemble the rear barrel portion 14 compositely with a forward barrel portion 12, in which a writing unit 26 and biasing spring 30 therefor have been loaded, in order to construct completely a writing instrument incorporating the latch mechanism of the present invention; and as aligned insertion of the writing unit 26 and biasing spring 30 in the forward barrel portion 20 requires no special aligning manipulation either, the further steps of completing the writing instrument construction can like wise be mechanized and accomplished automatically to provide an exceptionally simple and efiicient assembly method for production operation.

The present invention has been described in detail above for purposes of illustration only and is not intended to be limited by this description or otherwise except as defined in the appended claims.

We claim:

1. In a writing instrument comprising a barrel, a depressible plunger disposed for longitudinal sliding within said barrel and projecting beyond the rear barrel end, a writing element biased rearwardly within said barrel and slidably disposed therein to shift longitudinally between projected and retracted positions with respect to the forward barrel end, and a laterally rockable and longitudinally movable latch member disposed within said barrel rearwardly of said writing unit and forwardly of said plunger, said latch member being unattached to the writing element and having a rearwardly facing contact area and a laterally extending latching portion spaced longitudinally from said contact area, said barrel having longitudinally spaced latching shoulder portions disposed therein for releasably engaging the latching portion of said latch member for latching said writing element alternately at said projected and retracted positions, said plunger having a forwardly facing contact area disposed in opposing operative relation to said latch member contact area and being engageable with said latch member upon successive plunger depressions for laterally rocking said latch member alternately in opposite directions for engaging said latch member with alternate barrel latching shoulder portions, and said latch member upon each release of the depressed plunger after latching at one of said barrel latching shoulder portions being pivoted about said latching shoulder portion and thereby reset under the force of said writing element biasing means for opposite operating contact with said plunger upon the next succeeding depression thereof; the improvement comprising said latch member being a solid of revolution symmetrically formed about its longitudinal axis, the symmetrical for-m providing for operable engagement of said latch with said plunger contact area without requiring any specific orientation thereof about said longitudinal axis.

2. In a writing instrument, the improvement of claim 1 characterized further in that said symmetrical latch member is rounded rearwardly to a pointed rear end configuration.

3. In a writing instrument, the improvement of claim 1 characterized further in that the latching portion of said latch member is an annular shoulder and engageable with said barrel latching shoulder portions without requiring any specific orientation thereof about said longitudinal axis.

4. In a writing instrument, the improvement of claim 1 characterized further in that said plunger is a solid of revolution symmetrically formed about its longitudinal axis and the forwardly facing contact area thereof is engageable with said latch member contact area without requiring any specific orientation thereof about said longitudinal axis.

5. In a writing instrument, the improvement of claim 4 characterized further in that said forwardly facing contact area is a forwardly facing conical surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,757,639 Wichmann Aug. 7, 1956 2,865,333 Heehtle Dec. 23, 1958 2,930,354 Lockwood Mar. 29, 1960 2,930,355 Bollerup Mar. 29, 1960 2,930,356 Liguori Mar. 29, 1960 FOREIGN PATENTS 804,903 Great Britain Nov. 26, 19 58 

